From 5f2f05a57009cde33deccf83925d6963a2225662 Mon Sep 17 00:00:00 2001
From: Trinkle23897 <463003665@qq.com>
Date: Sat, 13 Jun 2020 17:06:08 +0800
Subject: [PATCH] fix #40

---
 tianshou/policy/modelfree/sac.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tianshou/policy/modelfree/sac.py b/tianshou/policy/modelfree/sac.py
index 9dd4b8a..2885fe1 100644
--- a/tianshou/policy/modelfree/sac.py
+++ b/tianshou/policy/modelfree/sac.py
@@ -101,7 +101,8 @@ class SACPolicy(DDPGPolicy):
         y = torch.tanh(x)
         act = y * self._action_scale + self._action_bias
         log_prob = dist.log_prob(x) - torch.log(
-            self._action_scale * (1 - y.pow(2)) + self.__eps)
+            self._action_scale * (1 - y.pow(2)) + self.__eps
+        ).sum(-1, keepdim=True)
         act = act.clamp(self._range[0], self._range[1])
         return Batch(
             logits=logits, act=act, state=h, dist=dist, log_prob=log_prob)